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FOR IMMEDIATE RELEASE
No. 2582
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Optical Communication Devices Marketing Sect.
Mitsubishi Electric Corporation
Tel: +81-3-3218-3332
[email protected]
http://www.mitsubishichips.com/Global/
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Mitsubishi Electric Corporation
Tel: +81-3-3218-3380
[email protected]
http://www.MitsubishiElectric.com/news/
Mitsubishi Electric Develops World's First Monolithically Integrated Laser
Diode for 43Gbps RZ-DQPSK Transmission
Tokyo, March 3, 2011 – Mitsubishi Electric Corporation (TOKYO: 6503) announced today that it has
developed a world’s first fully monolithically integrated laser diode for use in transmission devices that
transmits large data volumes between metropolitan areas at 43 giga-bits per second (Gbps) in a method
called Return to Zero Differential Quadrature Phase Shift Keying (RZ-DQPSK). Consisting of a tunable
laser array, an RZ Mach-Zehnder modulator and a DQPSK Mach-Zehnder modulator, this new laser diode
achieves tuning control over the range of 95channels at 40nm in standard set by the 50-GHz International
Telecommunication Union Telecommunication Standardization Sector (ITU-T). This breakthrough will be
presented at the Optical Fiber Communication Conference 2011 (OFC 2011) scheduled to be held at the Los
Angeles Convention Center in Los Angeles, CA on March 6~10, 2011.
Key Accomplishments
1. Monolithic integration on a single chip consisting of a tunable laser array, a Mach-Zehnder intensity
modulator and a Mach-Zehnder phase modulator
- Three functional chips are monolithically integrated into one, an industry first
(1) A tunable laser array whose wavelength can be controlled between 1572 nm and 1612 nm
(2) RZ Mach-Zehnder modulator which modulates the intensity of output power
(3) DQPSK Mach-Zehnder modulator which modulates signal phase
- The chip's dimensions are 9.6 x 0.75mm, less than one hundredth of the size of conventional chips
- The module’s volume, including the chip, can be minimized to less than one third of the size of
conventional modules
2. Realization of 43Gbps DQPSK operation and densely divided wavelength control for long distance and
high bit rate transmission
- The chip covers 95 channels of the 50 GHz ITU-T grid in L-band from 1572nm to 1612nm
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Future Development
In the future, Mitsubishi Electric plans to enhance the performance of high power, low consumption and
clear optical waveforms. The company also plans to develop a light source for C-band from 1530 nm to
1570 nm.
Background
Transmission volume over optical communication networks is rapidly increasing. The densely spaced
wavelength division multiplexed channels, higher bit rate transmission and multi-level formats such as
DQPSK are in demand for long distance transmission. Previously, it was common for transmission device
manufacturers to use several different chips such as the LiNbO3 Mach-Zehnder modulators and the tunable
lasers. However, the device size is several centimeters or more in length and requires relatively large driving
power. The fully monolithic integration and InP-based modulator effectively minimize device size and
power consumption. Mitsubishi Electric developed for the first time a 40G RZ-DQPSK transmitter
monolithically integrated with a tunable Distributed Feed-Back (DFB) laser array and Mach-Zehnder
modulators.
Features
1. Monolithic integration on a single chip consisting of a tunable laser array, a Mach-Zehnder intensity
modulator and a Mach-Zehnder phase modulator
The structure of a 43G RZ-DQPSK transmitter monolithically integrated with a tunable DFB laser array and
Mach-Zehnder modulators is shown in Figure 1.
Tunable laser array
LD array
(12 lasers)
RZ Mach-Zehnder
modulator
(intensity modulator)
DQPSK Mach-Zehnder
modulator
(phase modulator)
SOA
~
output
MMI
phase
modulation
waveguide
phase
shifter
phase
π/2-phase phase
modulation shifter
shifter
waveguide
Figure 1: Design of RZ-DQPSK transmitter
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2. The chip covers 95 channels of the 50 GHz ITU-T grid in L-band between 1572 nm and 1612 nm
A tunable laser array consists of 12 DFB lasers whose wavelengths are set at intervals of about 3.7 nm. 95
channels of the 50-GHz ITU-T grid in L-band can be achieved by controlling the temperature of the chip
Relative Intensity [dB]
between 25 and 65 degrees Celsius.
0
-10
-20
-30
-40
-50
-60
-70
-80
-90
-100
1570
1575
1580
1585
1590
1595
1600
1605
1610
1615
Wavelength [nm]
Figure 2: Optical spectrum of all generated channels
3. Excellent extinction characteristics were realized
Normalized Output Power [dB]
A high extinction ratio of 27dB and low driving voltage were realized.
5
0
-5
-10
-15
-20
-25
-30
-35
-2.5 -2 -1.5 -1 -0.5
0
0.5
1
1.5
2
2.5
Push-Pull Voltage [V]
Figure 3: Optical transmissions vs the applied dc voltage
About Mitsubishi Electric
With over 90 years of experience in providing reliable, high-quality products to both corporate clients and
general consumers all over the world, Mitsubishi Electric Corporation (TOKYO: 6503) is a recognized
world leader in the manufacture, marketing and sales of electrical and electronic equipment used in
information processing and communications, space development and satellite communications, consumer
electronics, industrial technology, energy, transportation and building equipment. The company recorded
consolidated group sales of 3,353.2 billion yen (US$ 36.1 billion*) in the fiscal year ended March 31, 2010.
For more information visit: http://www.MitsubishiElectric.com
*At an exchange rate of 93 yen to the US dollar, the rate given by the Tokyo Foreign Exchange Market on
March 31, 2010
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